Nitro-starch explosive.



'Uu'run STATES PATENT OFFICE. Y

JESSE B. BRONSTEIN AND CHARLES E. WALLER, OF ALLENTOWN, PENNSYLVANIA, I

ASSIG-NORS TO INDEPENDENT NON-FREEZING POWDER COMPANY, OF NEWARK, NEW JERSEY, A CORPORATION OF NEW JERSEY.

NITRO-STARCH EXPLOSIVE.

No Drawing. Application filed August 7, 1913, Serial No. 783,601.

Specification of Letters Patent.

Patented June 20, 1916.

Renewed January 8, 1916. Serial No.

To all whom it may concern Be it known that we, Jesse B. BRON- STEIN and CHARLES E. WALLER, citizens of the United States, and residents of Allentown, Lehigh county, Pennsylvania, have invented certain Improvements in Nitro- Starch Explosives, of which the following is a specification.

Our invention relates to nitro-starch explosives.

Heretofore nitro-starch explosives have been made containing nitro-starch as the explosive base, nitrate of soda as the'oxygen carrier and suitable quantities of an antiacid and of a water-proofing material. These powders have been graded to suit conditions encountered in practice by varying the percentage of nitro-starch and nitrate of soda. This type of explosive has been quite widely used and found satisfactory for many purposes.

The object of our invention is to improve said explosive by increasing its efficiency, decreasing its cost, and making this type of explosivemore generally applicable for all classes of work.

In order to economically develop the highest degree of energy the nitro-starch explosive should be so formulated as to permit of complete combustion when detonated without leaving any considerable percentage of free oxygen. That is to say, the oxidizable ingredients in the explosives should hear such a relation to the proportion of oxygen present as to result on ex plosion in the complete oxidation of all the oxidizable elements without leaving any considerable excess of free oxygen.

Nitro-starch has such an oxygen deficiency and nitrate of soda such an oxygen excess that 55 parts of nitro-starch and parts of nitrate of soda constitute such a mixture as will permit of complete combustion when detonated Without leaving any free oxygen. It follows, therefore, that more than parts of nitro-starch cannot be used in a nitro-starch explosive such as described above, with a properlyeconomical development of the entire energy of the nitro-starch.

For most purposes nitro-starch explosives containing 55 parts or less of nitro-starch are sufiiciently strong. Occasionally, howsible energy from the nitro-starch cannot be obtained under such conditions.

It is one of the purposes of this invention to provide a suitable substitute for a portion of the nitro-starch to be added in varying proportions in the difierent grades in such manner as to develop the same amount of energy as would be developed were the full amount of nitro-starch present, and at the same time permit of ad erence to the principle outlined above, 2'. e., that the relation of the'oxidizable elements to the available oxygen should be such that practically complete oxidation occurs upon explosion Without leaving any considerable percentage of free oxygen.

We have discovered that a mixture of nitrate of ammonia and trinitrotoluene may be added to the nitro-starch explosives and within certain limits will act as a suitable substitute for a portion of the nitro-starch for the purpose and in the manner above described. We have used with success, and prefer, a solid trinitrotoluene (sometimes known commercially as trinitrotoluol) having a melting point of from 78 to 80? C. However, we do not wish to be confined, in the broader aspects of our invention, tothe use of this particular trinitrotoluene, as other solid trinitrotoluenes having dilferent melting points may be employed, "and, in fact, there may be other solid nitrated hydrocarbons which could be used in' an equivalent manner with equivalent results for example, monoitronaphthalene.

' We have also found that certain mixtures of nitrate of ammonia and trinitrotoluene After the mixture has been heated for a sufficient period to permit the trinitrotoluene to soften the mixture is permitted to cool and is stirred until cold.

lVe have found that for some purposes an amount of the ammonium-nitrate-trinitro toluene mixture equal to '35 per cent. by weight of the entire explosive, may be substituted for a like amount of nitro-starch without detracting from the strength orusefulness of the explosive. The advantage of thus substituting some of the ammoniumnitrate-trinitrotoluene mixture for a ortion of the nitro-starch is not only that the full strength of the nitro-starch present is thus developed by reason of the proper balancing of the oxidizable elements and the available oxygen, but also because the resultant explosive is cheaper and of better physical condition. It also has the advantage that it is less liable to ignite from spark or friction than the ordinary nitro-starch powder of the same grade of strength.

An example of one composition illustrat- 1ing this feature of our invention is as folows:

mixture may be employed not only in nitrostarch explosives of the higher grades, but

also, with most of the advantages above referred to, in nitrostarch explosives of lower grades, but we have found that the substitution of the said mixture for a portion of the nitro-starch in explosives of the lower grades, leads to a considerable oxygen excess, which tends to reduce the temperature of the explosion, and consequently the strength of the explosive. Difiiculty has been encountered in overcoming this defect, both in this and in other nitro-starch powders, by reason of the fact that carbonaceous material, when added in a finely divided state in sufficient quantities to properly balance the oxygen content of the explosive, has the effect of unduly desensitizing. On the other hand, most forms of coarse carbonaceous material, such, for example, as coarsely ground coal, are not sufliciently susceptible to oxidation to permit of use for the purpose stated. We have discovered, however, that we can use to excellent advantage for this purpose, an ordinary cereal grain, such, for example, as wheat, when ground into a coarse, hard and granular form of such size that the grains will pass through a 20 mesh screen but not through a mesh screen, and having all of the finer material separated therefrom. This material we have found does not desensitize the explosive asdoes "the finely ground material, and at the same time it is very readily oxidized. Such material can be obtained as screenings from flour and starch mills, or can be specially prepared for use. Another good feature of this particular form of carbonaceous material is that it is nonhygroscopic, whereas finely divided starch or flour absorb moisture quite readily. In order to illustrate the beneficial effects of introducing a proper proportion of this material into ni ro starch explosives which would otherwise contain a considerable oxygen excess, it may be stated that we have ascertained by experiment that the addition of 6 per cent. of this material into an explosive containing 30 per cent. of Intro-starch hasthe effect of increasing the propellent force, as indicated by the ballistic mortar, about 10 per cent. Amounts of the carbonaceous material referred to varying from 1 to 10 per cent. by weight of the entire explosive mixture have given satisfactory resultsin varying decrees.

Experiment has shown, however, that the brisance or shattering force of the explosive is not increased by the addition of this carbonaceous material in the same proportion as the propellent force is increased. As it is highly desirable that the shattering force should increase proportionately with the increase of propellent force, experiments were performed to try to discover a material which could be added to give this effect. We have discovered that within certain limits the addition of small proportions of sulfur has the desired effect. We have discovered that the maximum increase of both the propellent force and brisance is effected by the introduction of sulfur and the carbonaceous preparation of wheat flour in about equal parts, the total of the two ingredients being so proportioned to the excess oxygen which would otherwise exist in the explosive as to just balance the amount of oxidizable elements with the amount of available oxygen. To further explain the effect of the carbonaceous material and the sulfur, it may be stated, that the presence of the carbonaceous material tends to increase the gaseous products of explosion, while the presence of sulfur tends to increase the temperature of explosion. The presence of sulfur in the quantities in which we use this ingredient also tends to increase the semitiveness of the explosive. Neither of the materials tend in any way to reduce the stability of the explosive, nor do they have an injurious effect on the physical condition of the explosive. In short, the introduction of these ingredients in the proportions in which we use them tends to materially increase both the propellent force and brisance of-the explosive without making any material increase in the cost of the explosive and without having any deleterious effect. In using both sulfur and carbonaceous material as hereinabove described, we have obtained satisfactory results with amounts of each ingredient varying from 1 to 10 per cent. by ture.

One illustration of an explosive employing our invention as thus far described, is as follows:

Nitro-starch, 30. 0% Ammonium nitrate-trinitrotoluene weight of the entire explosive mix- For some purposes sulfur may be usefully employed as an ingredient in a nitro-starch explosive in which a portion of the nitrostarch has been replaced by ammonium nitrate-trinitrotoluene mixture, where the use of carbonaceous material is unnecessary. fin instance of'such an explosive is as fol ows:

Nitro-starch Ammonium nitrate-trinitrotolu- 'C ene 20.0 Sodium nitrate 37.25% Sulfur 2. 00% Calcium carbonate r 1.00% Parafiin oil; ..;Q .75%

In the explosives which we have described above, the propellent force and the shattering force are so proportioned one to the other as to give the best results in all that class of work which involves moving great masses of rock in very large quantities. This class of work is exemplified in any of the large quarry or excavation operations where blasts comprising thousands of pounds. of explosives are frequently made and where thousands of tons'of stone are brought down witheach blast. In such work, in order to getv the best results from the energy of the explosive, it is necessary that neither the shattering force nor the propellent force of the explosive be unduly preponderant in the explosive. For instance, if the explosive has too great a brisance or shattering force too large a proportion slits total energy is consumed in pulverizing and burning the rock in immediate contact with the charge, thus resulting not only in a useless waste of energy but also having another bad efiect 1n that under these conditions the charge chamber is instantaneously enlarged at the moment of explosion before the main mass of rock or earth begins to move and before the gases have developed their full pressure with the their maximum pressure must act in an en-' larged chamber which has the effect-of reducing the pressure per unit area. On the other hand, if too large a proportion of the energy of the explosive is developed as propellent force the rock is thrown out in great masses which are difficult to handle in quarry or excavation operations". In the explosives which ,we have described in examples thus far given, the propellent force and shattering force are so proportioned to one another as to give the most efficient results in operations such as just described.

Inour experiments with nitro-starch ex-' plosives of the characterabove described, we have found that for use in underground operations where the rock is extremely hard and where it is necessary to have an explosive the energy of which is chiefly developed as shattering force? orbrisance,

the change of a certain proportion of the propellent force of the explosive into shattering force or brisance canbe effected by substituting within certain limits barium ,result that the gases when they do reach nitrate for-a portion of the sodium nitrate as the oxygen carrier.

Experiment has shown thatthe shattering force of nitro-starch explosives, such as we have described, may be increased about 20% by substituting about 30% of bariunn nitrate for a like proportion of sodium nitrate.- For effecting this result barium nitrate is particularly efficacious in those nitro-starch explosives /which would otherwise contain an oxygen 'excessand in those nitro-starch explosives which contain the ammonium-nitratetrinitrotoluene mixture. We ascribe the efiiciency of the barium nitrate for the purpose for which we use it to the following facts: In the first place it has a smaller oxygen excess than sodium nitrate and for this reason gives an increased temperature of explosion in those explosives WlllCh would otherwise contalna considerable excess of free oxygen. 'Sec- I ondly, it appears to carry its oxygen in a more readily available form. Thirdly, the specific gravity of barium nitrate is greater than that of sodium nitrate, thereby. resulting in a more dense charge which results in a greater shattering force by reason of the fact that the smaller the charge chamber for a given amount of explosive energy the-more violent will be the action of the explosive. on

the surrounding matter.

The addition of barium nitrate to nitrostarch explosives in the proportions which we describe also increases the susceptibility of the explosives to the effect of the detonating cap. Experiment has indicated that the facility with which the detonating wave passes through the powder is also increased by the presence of the barium nitrate, thus making it possible to secure better results in blasts Where long charges of powder are employed. Another good feature of the presence of barium nitrate in nitro-starch explosives is that it reduces the tendency to absorb moisture. Barium nitrate may be used for our purpose with success in amounts up to but not exceeding 40 per cent. by weight of the entire explosive mixture.

An illustration of one explosive containing all of the various ingredients which have now been described, is as follows:

1. An explosive containing nitro-starch as an explosive base, and a mixture of ammonium nitrate and trinitrotoluene, said mixture not exceeding substantially thirtyfive per cent. (35%) by Weight of the entire explosive.

2. An explosive containing nitro-starch as an explosive base and a mixture of ammonium nitrate and trinitrotoluene, said mixture comprising seventy to ninety parts nitrate of ammonium and thirty to ten parts trinitrotoluene.

3. An explosive containing nitro-starch as an explosive base, a mixture of ammonium nitrate and trinitrotoluene not exceeding substantially thirty-five per cent. (35%) by weight of the entire explosive, and from one (1) to ten per cent. of a hard granular, readily oxidizable carbonaceous material.

4. An explosive containing nitro-starch as an explosive base, a mixture of ammonium nitrate and trinitrotoluene not exceeding substantially thirty-five per cent. by weight of the entire explosive, from one to ten per cent. of a hard granular readily oxidizable carbonaceous material and from one to ten per cent. of sulfur.

5. An explosive containing nitro-starch as an explosive base, a mixture of ammonium nitrate and trinitrotoluene not exceeding substantially thirty-five per cent. (35%) by weight of the entire explosive, barium nitrate, not exceeding substantially forty per cent.. a hard granular readily oxidizable carbonaceous material, not exceeding ten per cent. (10%) and sulfur not exceeding ten per cent. (10%).

In testimony whereof, We have signed our names to this specification in the presence of two subscribing witnesses.

JESSE B. BRONSTEIN. CHARLES E. WALLER. Witnesses CHARLES H. HOWSON, J 0s. H. KLEIN. 

